GPU on Motherboard - no PCI transfers?

Does anyone have experience of GPUs built into the motherboard?
Can these do CPU memory <-> GPU faster than using the PCI bus?
[I have seen some mention of nVidia motherbaords but these still describe PCI suggesting it is still used for host-GPU communication.]
Many thanks

    Dr. W. B. Langdon,
    Department of Computer Science,
    University College London
    Gower Street, London WC1E 6BT, UK

EvoPAR 2012
EuroGP 2012 30 Nov
A Field Guide to Genetic Programming
GP Bibliography

With motherboard gpus it is always best to use zero-copy.
If you opt to not do so you have to do a memcopy as with conventional GPUs

Thank you.

Do you have any figures for the actual transfer rates you get for real?

Which GPU (and CPU and motherboard) are you using?

Thanks again